Dynamoelectric machines



April 2, 1957 J. TUDGE DYNAMO ELECTRIC MACHINES 2 Sheets-Sheet 1 FiledDec. 7, 1954 I .N'VENTOR ATTORNEYS A ril 2, 1957 Filed Dec. 7, 1954 J.TUDGE DYNAMO ELECTRIC MACHINES {/9 FIG. 2.

2 Sheets-Sheet 2 \NVENTOR M ATTORNEYS United States PatentDYNAMOELECTRIC MACHINES Joseph Tudge, Walkden, England, assignor toMetropolitan-Vickers Electrical Company Limited, London, England, aBritish company i Application December 7, 1954, Serial No. 473,587

Claims priority, application Great Britain January 19, 1954 3 Claims.(Cl. 310-61) This invention relates to dynamo-electric machines and hasan important application in large size turbo-alternators.

It is well known that one of the main factors limiting the output of alarge dynamo-electric machine, such as a turbo-alternator, is the risein temperature. This in turn depends upon heat dissipation, the limitingtemperature rise being of course the temperature rise of any individualpart or component.

It is customary to cool machines by promoting a flow of gas, such as airor hydrogen, over the surfaces of the core of the conductors.

The present invention is concerned with improving the cooling of therotor conductors.

. According to the present invention the rotor conductors are formedwith longitudinal passages, axially extending inlet ports to saidpassages formed in the exposed end turns, together with axiallyextending subslots in the core extending beneath the winding slots andarranged to be fed with cooling gas at each end of the core, radiallyextending ports between the sub-slots and the conductor passages withinthe winding slots and discharge ports between the conductor passages inthe winding slots and the rotor periphery.

With such an arrangement the coil ends and the embedded portions of thecoils are separately and independently ventilated.

Preferably the conductor passages are blocked at or near the ends of thecore so that the conductor passages along the mid-part of the core aresupplied with gas wholly from the sub-slots.

The radial ports in the embedded parts of the coils may be graded togive a desired distribution of gas flow.

The individual conductors may conveniently each be formed of a pair ofsuperimposed straps, which are channelled or grooved along theircontacting faces, so that when placed together they form an internalduct.

In order that the invention may be more clearly understood referencewill now be made to the accompanying drawing, in which:

Fig. 1 is a pictorial representation illustrating somewhatdiagrammatically the underlying idea of the invention, and

Figs. 2, 3 and 4 are enlarged cross-sectional views of a coil taken onthe lines IIlI, IIIIII, and IVIV, respectively.

In the drawing the reference 1 indicates the rotor core of aturboalternator. 2 are wedges closing the slot openings at the rotorperiphery. In the drawing there are shown two of the slots between whichis a core tooth 3. Extending through each slot is a coil 4, each coilcomprising a number of superimposed conductors separated by insulation.In the arrangement shown each conductor comprises an upper strap 5,superimposed on a lower strap 6, the upper straps 5 are grooved alongtheir under surfaces, whilst the lower straps 6 have correspondinggrooves in their upper surfaces so that when the two straps are laidtogether, one over the other, the grooves will register and formlongitudinal passages 7. These passages extend throughout theconductors.

It will be appreciated that in cooling conductors internally there aretwo main factors to consider. There is first the problem of cooling theexposed end turns, such as the end turn 8 shown in the drawing, andthere is also the problem of cooling those parts of the conductors whichextend through the slots in the core.

In accordance with the invention the external surfaces of the end turnsare cooled in the normal manner by air flow over these surfaces whilstthe interiors of the conductors are additionally cooled by cooling gasentering through axially extending ports 9 on the side faces of thecoils, whilst those parts of the conductors which are located in thecore slots are supplied with cooling gas through radial passages 10, fedfrom sub-slots 11. Thus the gas will enter through the ports 9 and thenpass along the longitudinal passages 7 into the core slots, whence itwill discharge through the two end radial ports 12, which extendradially outwards to the periphery of the rotor through the wedges 2.Stops 13 extend across the longitudinal passages beyond the radialdischarge ports 12, and so prevent the cooling gas from the end turnspassing further along the slots.

In this manner the ventilation of the embedded parts of the coil isentirely independent of that of the coil ends and different suctions maybe employed.

As above mentioned, the conductors within the slots, i. e., to the rightof the stops 13, are fed with cooling gas through a sub-slot 11, whichextends axially below each of the winding slots. Cooling gas enters ateach end 14 of a sub-slot and from the sub-slot passes radiallyoutwards, i. e. upwards in the drawing, through the radial ports it),which extend upwardly as far as the uppermost conductor passage, but donot extend as far as the periphery. The ports 10 are uniformly spacedalong the rotor and between each pair of ports 10 is a discharge port15, which extends to the periphery of the rotor in a similar manner tothe ports 12 at the end of the rotor. Thus, cooling gas from thesub-slots 11 passes up the ports 10, then along the conductor passagesand finally discharges through the ports 15.

It will be appreciated that with such an arrangement all parts of therotor winding are subjected to cooling, and the possibility of hot spotsis substantially avoided.

If desired the ports 10 and also the ports 15 may be graded to give adesired distribution of gas flow.

Whilst, in the actual arrangement shown, the gas from the end turnsdischarges through the two ports 12 in the slots, clearly more than twoports may be so employed if desired or even a single port.

The stops 13 may conveniently corn-prise insulating blocks extendingacross the passageway or, alternatively, they may be of conductingmaterial and may, for example, be formed of the actual material of theconductors, by omitting a short length of channelling.

Whilst in the actual arrangement shown the longitudinal passages areformed internally of the conductors, clearly other arrangements could beemployed, for instance, longitudinal channels could be formed in theexternal face or faces of the conductors and could be closed byinsulation over the top of the channel.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A dynamo-electric machine having a stator and a rotor having a coreprovided with winding slots, a winding having portions embedded in slotsin the rotor core and exposed end turns and comprising conductors havinglongitudinal passages form-ed therein, means formed in the exposed endturns of the winding and defining axially extending inlet ports leadingto said longitudinal conductor passages, means defining radiallyextending outlet ports situated within and close to the ends of therotor core and providing discharge means for said conductor passages inthe end turns of the winding to the rotor periphery, walls definingaxially extending sub-slots in the rotor core beneath the winding slotstherein, means for feeding cooling gas to said sub-slots at each end ofthe rotor core, means defining radially extending ports between saidsubslots and said longitudinal conductor passages, and means definingports between the conductor passages in the embedded portions of thewinding and the rotor periphery.

2. A dynamo-electric machine having a stator and a rotor having a coreprovided with winding slots, a winding having portions embedded in slotsin the rotor core and exposed end turns and comprising conductors havinglongitudinal passages formed therein, a cooling circuit for the exposedend turns of the winding including means defining axially extendinginlet ports to said conductor passages in the exposed end turns of thewinding, and means defining radially extending outlet ports situatedwithin and close to the ends of the rotor core and discharging to therotor periphery, a cooling circuit for the embedded portions of thewinding comprising walls defining axially extending sub-slots in therotor core beneath the winding slots therein, means for feeding saidsub-slots with cooling gas at each end of the rotor core, means definingradially extending ports between said subslots and said longitudinalconductor passages, means defining discharge ports between the conductorpassages in the embedded portions of the winding and the rotorperiphery, and blocks in said longitudinal conductor passages separatingsaid cooling circuit for the embedded portions of the winding from saidcooling circuit for the exposed end turns of the winding.

3. A dynamo-electric machine having a stator and a rotor having aslotted core, a winding having portions embedded in slots in the rotorcore and exposed end turns and comprising conductors having longitudinalpassages formed therein, a cooling circuit for the exposed end turns ofthe winding including means defining axially extending inlet ports tosaid conductor passages formed in the exposed end turns and meansdefining radially extending outlet ports situated within and close tothe ends of the rotor core and discharging to the rotor periphery,together with a cooling circuit for the embedded portions of saidwinding comprising walls defining axially extending subslots in therotor core beneath the winding slots, means for feeding said sub-slotswith cooling gas at each end of the rotor core, means defining radiallyextending ports between said sub-slots and said longitudinal conductorpassages, said radially extending ports being graded in cross-section togive a desired distribution in gas flow, means defining discharge portsbetween the longitudinal conductor passages and the rotor periphery, andblocks in said conductor passages and separating said cooling circuitfor the embedded portions of the winding from said cooling circuit forthe exposed end turns thereof.

References Cited in the file of this patent UNITED STATES PATENTS2,653,255 Baudry Sept. 22, 1953 2,664,512 Huntley Dec. 29, 1953 FOREIGNPATENTS 714,319 France Sept. 1, 1931

